SCR denitration system for cement kiln and technological process thereof

Abstract

The invention discloses an SCR denitration system for a cement kiln. The SCR denitration system comprises a preheater, an ammonia water conveying and spraying device, an SCR reaction tower, a power generation boiler, a returned ash conveying device and a high-temperature fan, wherein the outlet of the preheater is connected with the inlet of the SCR reaction tower through a pipeline I; the spraying opening of the ammonia water conveying and spraying device is connected with and arranged on the pipeline I in a sealed manner; ammonia water and waste gas are mixed to enter the SCR reaction tower;one outlet of the SCR reaction tower is connected with the returned ash conveying device; the other outlet of the SCR reaction tower is connected with the power generation boiler; the ash outlet of the power generation boiler is connected with the returned ash conveying device; the gas and ash outlet of the power generation boiler is connected with the high-temperature fan; and waste gas subjected to SCR denitration enters a next procedure through the high-temperature fan. According to the invention, the process characteristics of a cement firing system are fully utilized; a set of the SCR denitration system is arranged at the outlet of a kiln tail preheater; after NOx in the waste gas of the preheater passes through the SCR denitration system, a reaction of ammonia water and NO is promoted under the action of a catalyst; thus, NOx emission is reduced; denitration reaction efficiency is improved; and ammonia escape is reduced.

Description

technical field [0001] The invention belongs to the technical field of cement production equipment, and in particular relates to a cement kiln SCR denitrification system and a process flow thereof. Background technique [0002] As of the end of 2018, there were a total of 1,680 new dry-process cement production lines nationwide, and the actual clinker production capacity exceeded 2 billion tons. A large amount of NOx is produced during the production of cement clinker. According to statistics, NOx emissions from cement enterprises account for about 7% of the total NOx emissions in the country, seriously affecting the development of the national economy. At present, the most widely used denitrification technologies in the cement industry are staged combustion denitrification and SNCR denitrification. The staged combustion denitrification method has no operating cost and does not affect the normal operation of the firing system. The denitrification efficiency is about 30%, and...

AI Technical Summary

Problems solved by technology

At present, the most widely used denitrification technologies in the cement industry are staged combustion denitrification and SNCR denitrification. The staged combustion denitrification method has no operating cost and does not affect the normal operation of the firing system. The denitrification efficiency is about 30%, and the effect is stable, but it cannot meet the requirements of NOx. According to the requirements of the current national environmental protection standards, it can be used as the first step of denitration measures; and SNCR denitrification method, as a measure to further reduce the concentration of NOx emissions, has been widely used in the cement industry because of its simple system process and low investment. This method has problems such as low utilization efficiency, large consumption of reducing agent ammonia water, high ammonia escape, corrosion of pipelines and equipment, and secondary pollution.

[0003] The technology that can effectively control NOx emissions, improve ammonia water utilization efficiency, and reduce ammonia escape is SCR denitrification technology. This technology is rarely used in cement kiln flue gas denitrification projects and is still in its infancy.

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